Fibrous material and method of making same



Patented Oct. 11, 1932 UNITED STATES PATENT OFFICE JUDSON A. DE CEW, OF MOUNT VERNON, NEW YORK, ASSIGNOR TO PROCESS ENGINEERS, INCL, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK FIIBROUS MATERIAL AND METHOD OF MAKING SAME No Drawing. Application filed June 28,

This invention relates to a fibrous material, and more especially to a material or product which has had its pores filled with a waterproofing composition which is solid at ordinary temperatures but liquid at temperatures below 240 F. In order to make this product, which is the result of two years research a special kind of fibrous material is used, and also a special composition for impregnation.

The properties of the finished articles are such that they have a specific gravity of more than one and two-tenths (1.2). It has great strength, resists compression, is essentially waterproof, is not brittle, and cannot be fractured. This product is made from a fibre made on a wet-press machine, which builds up a product in thin layers or lamination until it has the required thickness.

A fibre board made in this way is much stronger than one that is made by pasting heavy pieces of paper together, or one that is formed in a solid mass in a press which has its fibres pointing in every direction and not felted together like a sheet of paper or fibre that is picked up on a cylinder mold. wet press fibre can be made in any thickness up to and as it is made by winding a thin sheet of paper pulp around one roll, it has the strength of many sheets of paper felted together into one and adhering to each other without any cementing material. This material after it is cut from the roll is pressed to remove excess water and then dried in a kiln. After it is taken from the kiln it may be passed between calender rolls to make it flat or to press it to a higher density.

In order to make this material sufficiently water-proof to give it wearing qualities in the presence of moisture, it must be impregnated with a special-composition which will surround the individual fibres and will keep them from absorbing more than five (5%) per cent of moisture on immersion. In order to give this material resistance to abrasion, it must be pressed until it is hard and dense. The dried material may first be impreg nated with the water-proofing composition and then pressed under heat until it reaches a high density or it may be first calendered to a high density and then impregnated with 1928. Serial No. 287,893.

the waterproofing composition. The latter method is generally preferable as it gives a somewhat stronger product; although heat and pressure may be thereafter applied to still further increase the density, if the greatest strength is desired.

The material used for impregnation is a composition of rosin and Montan wax in which the rosin predominates. Any hard wax other than Montan may be used as the purpose of this ingredient is to make the rosin more fluid and water repellant.

The wax must not be used to such an extent that it destroys the adhesive quality of the rosin. It has been found, however, that there can be used about equal proportions of rosin and wax and compositions containing less wax. In order to aid impregnation a small amount of solvent may be used to make the composition more fluid.

The fibrous material is impregnated by immersing it in a melted composition as above described. This impregnation may be accomplished either in an open tank, or in a closed tank where vacuum and/or pressure may be applied.

After the material is saturated w th the waterproofing composition, it is heated and pressed at the same time until it has a specific gravity of over 1.2, and which may even reach 1.4, or it may be calendered to a density of over 1.2 and then impregnated.

Because the final product is waterproof, it retains its hardness and resistance to wear even when exposed to wet conditions. It has many of the properties of vulcanized fibre, with the advantages of moisture resistance and freedom from inorganic chemical resi-v dues. Also the material has bending qualities, although it is essentially rigid.

This impregnated product differs from an ordinary paper product in many ways. A paper product may be made waterproof, according to ordinary terminology, by the use of rosin size in the pulp during the process of manufacture. The most water proof product that can be made in this way will absorb 20% of water on 24 hours immersion and will become soft and lose its strength and resistance to wear.

will retain its hardness and abrasive quali-.

ties.

Paper products have been impregnated for various purposes with materials such as wax, shellac, varnish and phenol condensation products. All of these materials have been tried, but it was found that although they may be suitable for some purposes, et they will not produce a product such as t at here described, which is suitable for rail joint insulation and other uses requiring similar properties.

A fibre product impregnated with a wax has no binding action on the fibres and is rel atively soft. .Varnishes are suitable for surface treatment but do not make a hard product when used by impregnation. Shellac may be suitable for electrical properties but will not make a waterproof product. Phenol condensation products make a productthat is too hard and brittle, and which has no compressibility.

In the process of impregnation it is necessary that the moisture and air in the fibre be first removed in order to get the composition to penetrate properly even when hot and fluid. When the fibre is immersed in the hot composition in an open tank, the mois ture and air are expelled, after which the melted mass will penetrate the fibres of the material. And when treated in a closed tank the fibre is heated, and a vacuum is applied to remove the moisture and air. After this it is immersed in the melted composition and a pressure applied to force it into the fibres.

After the material is completely impregnated and excess material is removed and the resulting material is cooled, it is then in condition to be formed into the finished articles. If it is desired to bend or form the material into special shapes, it may be first steamed or soaked in water to allow 3% or 4% of moisture to get back into the cellulose, and after that it can be pressed into special shapes with the aid of heat and pressure.

The special properties of this material are as follows: It is essentially a fibrous mass in which the strength and resistance modifications of the invention will be read- 11y ap arent, and it will also be obvious to such ed persons that part of the method and means may be used without other'parts thereof, many such combinations of the parts readily suggesting themselves. Therefore, it should be,and is to be distinctly understood that for a definition of the limitations of the invention, reference must be had to the appended claims.

Having now described the invention, what is claimed as new, and for which Letters Patent of the United States is desired, is:

1. A method of making waterproof fibrous material including the steps of forming the material in a wet-press machine to build it up in laminations to the desired thickness, drying it, impregnating it by immersion in a melted composition of rosin containing wax, and pressing it under heat to a specific gravity of over one and two-tenths.

2. A method of making a fibrous insulating material which includes the steps of forming the material on a wet-press machine, drying it, impregnating it by immersion in a melted composition of rosin containing wax, and pressing it under heat to a density of more than 1.2.

3. A method of making a dense moistureproof fibrous sheeted material, which includes the steps of forming a laminated sheet of fibre on a wet press machine, drying it, wholly impregnatingit by immersion in a melted waterproof composition, and then compressing it under heated plates to a density of over 1.2.

Signed at New York, in the county of New York and State of New York, this 19th day of June, A. D. 1928.

JUDSON A. DE CEW. 

